This invention relates to an electrochromic (hereinafter referred to as xe2x80x9cECxe2x80x9d) antiglare exterior rearview mirror that is mounted for example on a side panel or door of automobiles or other vehicles.
In general, an EC antiglare mirror takes the form of an assembly including a panel (support plate) and a mirror mounted on the panel, and the mirror is formed of a transparent glass plate and a reflective coating spread over a back surface of the transparent glass plate to form a reflective surface of the mirror. The EC antiglare mirror assembly is capable of varying reflectance of the reflective surface from a normal condition of total internal reflection (with antiglare effects disabled) in response to an electric charge given to the reflective coating, and thus enabling antiglare effects to show up.
A conventional exterior rearview mirror system (hereinafter referred to as xe2x80x9cexterior mirrorxe2x80x9d) comprised of such an EC antiglare mirror assembly is typically mounted on the outside of a vehicle body A, as shown in FIG. 7. For example, in FIG. 7, an exterior mirror 1 such as a door mirror, side mirror and the like is controlled to have an appropriate level of charge applied in such a manner as to coordinate with an interior rearview mirror system (or xe2x80x9cinterior mirrorxe2x80x9d) M that is comprised of an EC antiglare mirror assembly mounted on an upper portion of the windshield inside the vehicle body A.
The control of charge applied to the reflective coating in the above EC antiglare mirror assembly is, to be more specific, carried out using sensors that are provided in the vehicle body A to detect intensity of light from the surroundings or rearward, which intensity of light detected by each sensor is compared in an electronic control circuit, so that an automatic adjustment is made in antiglare levels. The electronic control circuit and other components are also provided in the vehicle body A where the interior mirror M is mounted, and a battery is installed in the vehicle body A and is used as a power supply for controlling electric charge to produce proper antiglare effects of the exterior mirror 1.
A conventional antiglare effect control system as described above is configured to switch the interior mirror M from a condition of total internal reflection (i.e., non-antiglare condition) to an antiglare condition, in cases where intensity of light detected by each sensor provided inside where the interior mirror M is mounted is much higher than ambient light, especially in night driving when light from rearward by a succeeding car or the like is intense, so as to dazzle a driver.
However, in the above-described conventional antiglare effect control system, no sensor that individually detects intensity of light from surroundings and rearward is provided outside where the exterior mirror 1 is mounted. Thus, as shown in FIG. 8, for example, when light-shielding film F is stuck on rear-panel glass of the vehicle body A, the detected intensity of light incident from the rear of the vehicle body A through the light-shielding film F into the interior mirror M is reduced to a level lower than an actual level of intensity of light. Accordingly, electric charge applied in the exterior mirror 1 would disadvantageously be controlled to produce antiglare effects that could be preferable only for the interior mirror M, so that desirable antiglare effects might not be achieved for a driver, et al.
Moreover, the use of a battery installed in the vehicle body A as a power supply for controlling electric charge to produce antiglare effects in the exterior mirror 1 not only requires burdensome wiring from the battery to the exterior mirror 1, but also aggravates the difficulties of replacement upon breakdown or damages, or of new installation for replacing an existing mirror system with the instant exterior mirror 1. Further, a mirror housing of the existing mirror system has no space necessary for mounting each sensor, and thus the mirror housing itself needs redesigning and reworking when the instant exterior mirror 1 is adopted; consequently extra costs may be incurred.
Recently, automobiles provided with a privacy enhanced screen glass window have been increasing in number. Such a privacy enhanced screen glass window installed automobile need not include an interior mirror system having an antiglare function because the privacy enhanced screen glass window may help reduce glare of light from rearward by a succeeding car or the like so that the light reflected off the interior mirror and getting to the eyes of the driver, et al. is not so intense as to dazzle the driver, et al. In contrast, light reflected off the exterior mirror directly enters the eyes of the driver, et al. through a side window of the vehicle body, and thus more likely dazzles the driver, et al. Accordingly, the privacy enhanced screen glass window installed automobile need include the exterior mirror system having an antiglare function.
The present invention has been made with consideration given to the above-discussed circumstances, and it is an exemplified object of the present invention to provide an exterior rearview mirror that has an independent antiglare function according to the intensity of light from surroundings and rearward to constantly produce optimum antiglare effects for a driver, et al., while facilitating replacement upon breakdown or damages of an existing exterior mirror system, and new installation for replacing an existing mirror system with the instant exterior mirror system.
In order to achieve the above object, there is provided, according to one aspect of the present invention as set forth in claim 1, an exterior rearview mirror system mounted on an outside of a vehicle body, comprising a mirror housing and a mirror assembly that is detachably attached to an open side of the mirror housing, forming a reflective surface of the mirror system. In this mirror system, the mirror assembly is composed of a mirror and a support plate for supporting the mirror, which mirror is made up of a transparent glass plate with a reflective coating spread over a back surface of the transparent glass plate, through which reflective coating electric current passes to produce an antiglare effect. In addition, the mirror housing contains a first sensor that detects intensity of light from surroundings of the vehicle body, a second sensor that detects intensity of light from rearward of the vehicle body, an electronic control circuit that compares the intensity of light detected by the first and second sensors, thereby controlling the electric current in the reflective coating so as to automatically adjust an antiglare level, and a battery that is connected with the electronic control circuit to supply the electric current into the reflective coating.
This construction provides an exterior mirror comprehensively incorporating all functions of detecting light from surroundings and rearward of a vehicle body, achieving an antiglare effect, and supplying electric current. Thus, independent control of electric current to appropriately adjust antiglare levels without coordinating with the EC antiglare interior mirror as a conventional antiglare effect control system requires becomes possible, and a complicate task for wiring from a battery provided in the vehicle body may be dispensed with. Moreover, provision of a dedicated battery allows electric current to be optimized so as to produce an optimum antiglare effect. Further, an antiglare level of the interior mirror never affects an antiglare effect control in the exterior mirror, and thus an optimum antiglare effect may be constantly achieved even if light-shielding film is stuck on rear-window glass of the vehicle body, or a privacy enhanced screen glass window is installed in the vehicle body.
According to another aspect of the present invention as set forth in claim 2, the mirror assembly in the above exterior rearview mirror system as set forth in claim 1 may have a modular structure in which the first and second sensors, the electronic control circuit, and the battery are combined into one unit.
This construction serves to easily achieve tasks of replacing an existing non-antiglare mirror system with an antiglare mirror system, or replacing the mirror system upon breakdown or damages, only by replacing the mirror assembly mounted in the mirror housing. Moreover, this construction, which never requires working the mirror housing, serves to reduce costs.
According to yet another aspect of the present invention as set forth in claim 3, the mirror assembly in the above exterior rearview mirror system as set forth in claim 1 may have an aperture formed in part of the reflective coating so that the first and second sensors provided adjacent to each other on the support plate face the transparent glass plate through the aperture, and a light-shielding cover that intercepts only light from rearward of the vehicle body may be provided on a front surface of the mirror right opposite to the first sensor.
This construction may serve to exclude an influence of light from rearward of the vehicle body, and thus especially allows the first sensor to detect intensity of light from surroundings of the vehicle body with high accuracy and real precision.
According to yet another aspect of the present invention as set forth in claim 4, a light-shielding plate may be interposed between the first sensor and the second sensor in the above exterior rearview mirror system as set forth in claim 3.
This construction may serve to eliminate interference between light from surroundings and light from rearward of the vehicle body, and thus allows the first and second sensors to detect intensity of light with high accuracy and real precision.
According to yet another aspect of the present invention as set forth in claim 5, the first and second sensors in the above exterior rearview mirror system as set forth in claim 1 may be so provided that the first sensor faces a frame of the mirror housing except the open side thereof, while the second sensor faces the open side of the mirror housing.
This construction allows detection of intensity of light from surroundings and rearward of the vehicle body to occur with great efficiency and high accuracy.
According to yet another aspect of the present invention as set forth in claim 6, the first and second sensors in the above exterior rearview mirror system as set forth in claim 1 may be so provided that the first sensor face a frame of the mirror housing except the open side thereof, while the second sensor is located on the support plate of the mirror assembly so that the second sensor faces the transparent glass plate through an aperture formed in part of the reflective coating.
This construction also allows detection of intensity of light from surroundings and rearward of the vehicle body to occur with great efficiency and high accuracy.
Other objects and further features of the present invention will become readily apparent from the following description of preferred embodiments with reference to accompanying drawings.